<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>盒模型</title>
    <style>
      article {
        border: solid 3px #ddd;
      }
      div {
        border: solid 3px red;
        margin: 30px;
        padding:20px 
      }
    </style>
  </head>
  <body>
    <article>
      <div>houdunren.com</div>
    </article>
  </body>
</html>
